What could possibly go wrong: how would this plan prevent enterprising entrepreneurs from "harvesting" the atmospheric diamond dust and repurposing it for "bling" or industrial applications? ᐧ
On Mon, Oct 26, 2015 at 12:54 PM, Andrew Lockley <andrew.lock...@gmail.com> wrote: > > http://www.nature.com/news/climate-scientists-ponder-spraying-diamond-dust-in-the-sky-to-cool-planet-1.18634 > > News & Comment > News2015October > > NATURE | NEWS > > Climate scientists ponder spraying diamond dust in the sky to cool planet > > Solid particles of diamond or alumina might be safer than sulphate > droplets as a way to redirect the Sun’s energy, calculations suggest. > > Andy Extance > > 26 October 2015 > > Injecting materials in the stratosphere is seen a desperate but feasible > 'geoengineering' measure to counter the effects of global warming. > > Climate scientists have thought up plenty of futuristic ways to cool the > planet, but an analysis published on 26 October1 examines what may be their > wildest idea yet: spraying tiny diamonds high into the atmosphere. > > Researchers have for years discussed the merits of pumping water-based > sulphate spray into the sky to reflect and scatter the Sun's energy — > essentially, mimicking the cooling caused by volcanic eruptions. Like most > kinds of geoengineering, the idea is highly controversial and so far > untested. > > But if anyone does try this 'solar-radiation management', then it may be > safer to use dusts of solid, nanometre-sized particles, suggests a team of > scientists from Harvard University in Cambridge, Massachusetts. In a paper > published in Atmospheric Chemistry and Physics1, they calculate that > nanoparticles of diamond or alumina (aluminium oxide) could be more > effective and less environmentally damaging than sulphates. And although > diamond dust is expensive, it is not completely out of the question, the > researchers argue. > > Related storiesClimate geoengineering schemes come under firePolicy: Start > research on climate engineeringClimate tinkerers thrash out a plan > > "Our paper is really geared towards removing the mindset that it has to be > sulphate that's used to do solar radiation management," says Debra > Weisenstein, an atmospheric modelling expert at Harvard and one of the > study's authors. > > Sulphate's side-effects > > Other researchers have proposed spraying solid dusts before2. But the > latest study is the first to model the particles' effects in detail, > Weisenstein says, by examining how they interact — both physically and > chemically — with different substances in the atmosphere, and making the > comparison with sulphates. > > In the atmosphere, sulphates lead to the production of sulphuric acid, > which damages the ozone layer. By absorbing certain wavelengths of light, > they also heat up the lower stratosphere; that in turn could affect > air-circulation patterns and climate. Sulphates would also diffuse light, > an effect that could boost plant growth but would lower the power output of > solar panels3. > > Alumina and diamond dust both lead to fewer problems, says > Weisenstein. “You could have significantly less impact on ozone, less > heating of the stratosphere and less of an increase in diffuse light at > Earth’s surface,” she says. That is because alumina and diamond do not > result in the production of sulphuric acid, and they scatter and absorb > particular wavelengths of light in a different way. > > Besides analysing environmental effects, the paper also shows that, pound > for pound, alumina dust would achieve a similar cooling effect to that of > sulphate sprays — but that diamond dust would be at least 50% more > effective. > > Diamonds in the sky > > Of course, spraying diamond dust into the sky would ring up a hefty bill. > Diamond dust is less expensive than cut gemstones: tiny synthetic diamond > particles are now available at less than US$100 per kilogram, the Harvard > researchers note. But based on their paper's results, offsetting just a few > percent of the energy trapped by human-emitted greenhouse gases would take > hundreds of thousands of tonnes of dust annually. Although the Harvard > researchers stress that they didn’t do a detailed cost analysis, at current > prices that would still require billions of dollars each year. > > However, Weisenstein is adamant that the ultimate cost would be lower. > "Once this can be scaled up to make the right quantities, you assume the > price is going to drop," she says. "Trying to estimate based on how much > diamond costs currently is not particularly useful." > > And David Keith, a climate scientist also at Harvard and another of the > paper's authors, says he does not think even today's costs would be > prohibitive. By 2065, he says, with 10 billion people on the planet, the > cost might be on the order of $5 per person to pump up some 450,000 tons of > diamond dust. > > Still, the Harvard team is focusing on alumina right now, Weisenstein > says, because it’s easier to make and its chemical behaviour has been > better studied. > > The scientists warn, however, that both alumina and diamond nanoparticles > carry unknown risks. Sulphates are reasonably well understood, thanks to > research on volcanoes. By contrast, the chemistry of the solid particles — > such as how their surfaces catalyse chemical reactions — is not as clear, > although the Harvard researchers are doing lab tests to remedy that. > > The study "strongly suggests" that such solid dusts could significantly > lower some of the risks associated with sulphates, says Matthew Watson, a > volcanologist at the University of Bristol, UK, who was the principal > investigator on one cancelled small-scale geoengineering experiment, the > Stratospheric Particle Injection for Climate Engineering project, or SPICE. > But he suspects that the unknown risks and lack of any natural analogue > will make solid dusts even less popular with the public than are sulphate > sprays. > > Nature doi:10.1038/nature.2015.18634 > > References > > Weisenstein, D. et al Atmos. Chem. Phys. Discuss.15, 11799–11851 (2015). > > Article > Show context > > Pope, F. D. et al. Nature Clim. Change 2, 713–719(2012). > > Article > ChemPort > Show context > > Kravitz, B. et al. Geophys. Res. Lett. 39, L11801 (2012). > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
